[sc34wg3] New TMCL slides: at least 2 roles must be played

Patrick Durusau patrick at durusau.net
Mon Nov 23 19:36:23 EST 2009


Steve Newcomb wrote:
> Patrick Durusau wrote:
>> Steve,
>> Steve Newcomb wrote:
>>> Lars Marius Garshol wrote:
>>>> I can see a need for omissible role types in n-ary relationships 
>>>> where it may be the case that one of the role players is not known, 
>>>> but in binary relationship then if one of the players is not known 
>>>> you can simply omit the entire relationship.
>>> I like this rule, but I think it should be more general. Even in an 
>>> n-ary association, if there's only one role player, there's no 
>>> relationship, so the whole association is otiose. The rule should 
>>> be: /At least two roles must be played/.
>>> The only thing that bothers me about this rule is that there may be 
>>> moments when an association is only partially expressed. But I'm not 
>>> sure that it's an issue, really.
>> Moments when an association is only partially expressed?
>> Hmmm, ok, what about marriage and one role player known but spouse is 
>> not? A partial baptism record for example. Not ever going to cure 
>> that lack.
>> May not know who the other role player is but the existence of the 
>> association is not in doubt.
>> A subject is lost by omitting the association. That is "a" choice but 
>> it isn't one that should be a rule for all topic maps.
> "Unknown role player" is very different from "unplayed role".
> I would claim that in the example you provide, the role is not 
> unplayed. It is played by an unknown person, at least if the 
> relationship is known to exist. I guess if there's a baby to be 
> baptized, that's evidence enough that a relationship exists, since 
> human reproduction takes two to tango.
If you want to *define* the subject "association" to consist of at least 
two roles, both of which are played but one of the players may be 
unknown, I suppose.

What puzzles me is why object to an "unplayed role?"

Hmmm, ok, say that I play the grandfather role in a grandfather <-> 
grandchild association. The later role isn't unknown but in fact 
unplayed, at least at this point in time. ;-)

Why would you object to my instantiating such an association in my topic 

Or is the issue actually what sort of associations are thought to be 
supported by the TMDM?

Hope you are having a great day!


Patrick Durusau
patrick at durusau.net
Chair, V1 - US TAG to JTC 1/SC 34
Convener, JTC 1/SC 34/WG 3 (Topic Maps)
Editor, OpenDocument Format TC (OASIS), Project Editor ISO/IEC 26300
Co-Editor, ISO/IEC 13250-1, 13250-5 (Topic Maps)

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